Katana Intermittant Power Loss

[Ted Veitch]

Within the silencer box of a Katana DA and DV model are the usual 'baffles'. If one, or a part of one breaks of, it may cover the single exaust exit port, presenting loss of power! There is no structure within the exaust pipe to prevent this! Jockying the throttle (changing pressure) may dislodge or shift the item and power will return. The problem is usually of a highly intermittant nature, as the offending part shifts around as a result of landings/take offs etc.
This 'problem' may be known in "some" circles, and may prevail on other aircraft for all I know, but I thought it deserves wider awareness. As the Katana model described usually only has an 85HP engine, we need all the horses we can get!

[john_tullamarine]

.. if this is a known problem ... why has the muffler not been redesigned ? .... very easy to fix this sort of problem ...

[Ted Veitch]

I fully agree - it is easy to resolve! (I believe according to recent information, the Bulldog silencer box has what can only be described as a wire 'mitre hat' at the internal entrance to the exhaust pipe to prevent its obstruction and allow gasses to pass almost unheaded). So why isn't something done about it! For my part, we have reported back to the appropriate locations.
Its interesting to know that investigation into the original situation/ problem was instigated by manufacturing sources!! The real question is how long has awareness of the problem been around, and as a safety issue, what would be the best vehicle to communicate matters such as these to other operators?

[Genghis the Engineer]

What should happen is these faults should be reported back to the TC holder via the MOR system. They should then either independently, or if they don't with the severe encouragement of their airworthiness authority, issue an SB notifying operators of the problem and if rectification work is needed, the local authority should have issued an AD mandating it.

I know nothing about the type, but that's the legal process by which it should happen. If it doesn't seem to be, best bet would be to first check if the known incidents have been MORed. If they have, then talk to the local CAA regional office, if not give the operators a polite phone call and remind them informally that they are in breach of the ANO - that generally gets things moving :O

G